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.TH PCAP_LOOKUPDEV 3PCAP "8 September 2017"
.SH NAME
pcap_lookupdev \- find the default device on which to capture
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.nf
.ft B
char errbuf[PCAP_ERRBUF_SIZE];
.ft
.LP
.ft B
[DEPRECATED] char *pcap_lookupdev(char *errbuf);
.ft
.fi
.SH DESCRIPTION
.B This interface is obsoleted by
.BR pcap_findalldevs (3PCAP).
To find a default device on which to capture, call
.BR pcap_findalldevs ()
and, if the list it returns is not empty, use the first device in the
list.  (If the list is empty, there are no devices on which capture is
possible.)
.LP
.B If
.BR pcap_init (3PCAP)
.B has been called, this interface always returns
.BR NULL .
.LP
.BR pcap_lookupdev ()
returns a pointer to a string giving the name of a network device
suitable for use with
.BR pcap_create (3PCAP)
and
.BR \%pcap_activate (3PCAP),
or with
.BR pcap_open_live (3PCAP),
and with
.BR pcap_lookupnet (3PCAP).
If there is an error,
or if
.BR pcap_init (3PCAP)
has been called,
.B NULL
is returned and
.I errbuf
is filled in with an appropriate error message.
.I errbuf
is assumed to be able to hold at least
.B PCAP_ERRBUF_SIZE
chars.
.SH SEE ALSO
.BR pcap (3PCAP)
.SH BUGS
The pointer returned by
.BR pcap_lookupdev ()
points to a static buffer; subsequent calls to
.BR pcap_lookupdev ()
in the same thread, or calls to
.BR pcap_lookupdev ()
in another thread, may overwrite that buffer.
.LP
In WinPcap and Npcap, this function may return a UTF-16 string rather
than an ASCII or UTF-8 string.
